Two of the oldest structures in New York were just demolished on Henry Street, 22 and 24: a four story row house and, next to it, a diminutive, narrow town house. Both must have dated at least as back as the 1820's; the town house may have dated back further. I did not have time to inquire about what is replacing it, but there is a girder structure up already.
The screen caps attached, cut from google street maps, don't do justice to them. They were a striking little piece of the early 19th century, unusual because of the pairing of a town house-with-dormers adjacent to a row house with a fully built fourth floor covered by a unique wood awning in lieu of a cornice. I always took visitors to see them on the Chinatown/Five Points tour. After the Mooney House, they were the oldest buildings around, and almost unaltered.
The demolition of a town house in Greenwich Village would spark a protest, an outrage and an angry movement, but far to the east in Chinatown, no preservationists seem to notice or care. And yet, these two small buildings were probably older than anything in the Village, and in a neighborhood with a much longer and complex history.